Helicobacters have emerged as a major problem for mouse-based research, directly causing disease, misinterpretation of phenotype in genetically altered animals, and alteration of experimental results. Infection is prevalent and spreading due to inter-institutional traffic of mice. Current diagnostic assays, based upon culture, membrane antigens or polymerase chain reaction, are not practical or amenable to large-scale testing, so there is need to develop cost-effective and efficient assays for testing serum or feces of infected mice. This project will identify immunogenic proteins of Helicobacter hepaticus and Helicobacter bilis by screening genomic expression libraries with immune serum from infected mice, then clone, sequence and express candidate recombinant proteins for development as species- and genus-specific antigens for serodiagnostic assays. The antigens will also be utilized to develop species- and genus-specific monoclonal antibodies that can be used for antigen-capture assays for testing feces. The species- and genus-specificity of these assays will be tested with sera from mice experimentally infected with clonal populations of Helicobacter hepaticus, Helicobacter bilis, Helicobacter muridarum, Flexispira rappini, and Helicobacter rodentium, if available.